Geothermal Energy: An Alternate Source of Energy

Code No:TMS153Price:Rs2300/-Category:Energy: Conservation

 

Summary  : This report highlights the available technologies world over for utilisation of Geothermal Energy. It also identifies areas in India where maximum benefit can be derived from Geothermal Energy. Considering the fact that fossil fuels are limited in quantity and fast depleting, as more than 90% of the world\'s energy needs are being met by fossil fuels Geo Thermal Energy is a very attractive alternate source of energy. With an objective of looking ahead at technologies, TIFAC has brought out a report on Geothermal Energy, which deals in depth the present status of technologies for exploration & utilization of geothermal energy in India and abroad. Geothermal resource base for India has been estimated as 3.8X105 Quads (1Quad =2.93X1011Kwhth) whereas the generation of electricity in India in 1997-98 stood at 4.2 Quads which reflects the enormous potential of this energy. The report also details the different uses of geothermal energy in different parts of the world such as power generation, agriculture, aquaculture etc. The report also identifies areas in India where maximum benefit can be derived from Geo Thermal energy, such as Puga valley in Laddakh, Tattapani in Sarguja district in M.P, Tapoban in U.P etc and its utilities in these regions.

Year of Publication : 1999

Table Of Contents : List of Tables, List of Figures, List of Appendix, Abbreviations & Acronyms, Units of Measurement Conversion Factors, Executive Summary, Importance of topic, Introduction History & Versatility of earth heat, Geothermal areas in world and renewability of geothermal resources, Geothermal exploration, drilling & bore fluid characteristics, Reservoir engineering, geothermal fluid collection, Electric utilisation of geothermal resources, Non-electric utilisation of geothermal resources, Dual and multipurpose geothermal energy utilisation, Control and safety of geothermal installations, Environmental issues Chemical and metallurgical, problems in utilisation plants, Economics & cost considerations, Miscellaneous points, R&D activities and future, Relevance to India, recommendations and action plan, Impact & spin offs if all the recommendations are implemented, Appendix I to VII References

  • Scope and Objective of the Study
  • Importance of Topic
  • Methodology
  • Limitations
  • Market Survey Response
  • Findings of study/survey analysis
  • Recommendations, Action Plan & Impact

The Techno-Market Survey "Geothermal -An alternate source of energy" focuses on the present status of exploration & utilization of this energy resources in India and world over. The exploration and exploitation of geothermal resources got a boost following the 1973 oil crisis world over. R & D activities were directed towards exploration & exploitation of various types of geothermal resources such as hydrothermal, geopressurised, hot dry rock, magma. In India also lot of efforts have been put up by Geological Survey of India in identification and exploration of various sources of geothermal energy which mainly include hydrothermal sources. The estimated energy in only one third of known thermal spring areas is 10,600 MWth. Geothermal energy has been put to varied uses in different parts of the world. The uses include power generation, direct use of heat for space heating, agriculture, aquaculture industrial processes, balneology, tourism etc. The geothermal fluid has also been used for mineral extraction & water resources. The status of utilization of geothermal energy in India at present is on symbolic level only as compared to the availability of the resources. Efforts are required to be directed for utilization of the resources, which have been identified for development, in backward, hilly and tribal regions in India, where maximum, benefit from geothermal resources can be derived as cost of energy sources through conventional means is also high there e.g. Puga - Chhumathang in Ladakh. (J&K), Tattapani in Surguja District (M.P.), Tapoban (U.P.) etc. Technology for utilization of geothermal energy at such a scale is available in our country.

As far as the status of utilization of geothermal resources world over, the electric utilization is nearly 8000 MW by the end of year 1997; the leading countries are Italy, New Zealand, USA, Japan, Philippines, Indonesia, Mexico, etc. In non electric utilization of geothermal energy the countries leading in use of geoheat for space heating, agricultural & industrial usages are Iceland, France, China, Japan, Hungary, USSR, USA, New Zealand, etc. World over utilization of geothermal energy for non-electric applications was to the tune of 12,000 MWth in the year 1991, Advanced technology is available for large scale utilization of geothermal energy in developed countries e.g. USA, Italy, Japan, France, New Zealand etc.

 

Scope and Objective of the Study

The scope and objective of the study as given by TIFAC is to address the following aspects in the context of the topic under study.

  • Relationship and the importance of the topic to the broad area to which it belongs.
  • The current status of the technology in the world and in India, Market sizes and their potentialities.
  • Assessment of technology, resource parameters such as energy, raw material, infrastructure etc., to arrive at preferred technology options available in the country.
  • Short term and long term economic aspects of preferred options along with their feasibilities.
  • Impact of preferred options and its spin-offs.
  • Recommendations :
  • For implementation of preferred technology options - identifying critical inputs such as occurrence and availability of raw material, capital goods and human resources required and their, expected benefits etc.
  • For R & D/technology development-identifying the requirements of inputs and expected benefits.
  • Action plan for implementation of recommendations alongwith identification of :
  • List of available technology for Indian Industry and
  • The agencies/group/individuals for implementation.
  • Expected impact of recommendations; if implemented.

 

Importance of Topic

Geothermal energy is contained in underground reservoirs of steam/water and hot dry rocks. Man’s appetite for energy is increasing day by day. World Energy conference Survey of Energy Resources estimated in 1980 that proved recoverable reserves of fossil fuels to last 131 years at world consumption level of 1972. To avert the situation new energy sources are to be found and to reduce the growth rate of energy demand to zero, or even reverse it. ‘Non-fuel’ energy sources becoming important, gone are the days of cheap energy. Reduction in growth rate of population will go a long way to reduce the growthrate of energy demand. As per energy consumption scenario in India, the per capita energy consumption is low but the growth rate of energy consumption is high in India, being a developing country utilisation of geothermal energy is one of the options. With energy demand multiplying, none of the reasonably accessible source can be allowed to go waste. The probable shape of things to come in future world energy supply will be ultimately limited to renewable sources alone.

Gigantic efforts have already been made by GSI in close ordination with NGRI, ONGC, MECL, CEA, BARC, UOR, IIT Delhi in the field of exploration of geothermal resources in India and the estimated energy in only one third of known thermal spring areas in the country is 10,600 MWth. If this energy is exploited for the benefit of society, development of backward, hilly & tribal areas can get a boost.

 

Methodology

The Techno-Market Survey was conducted through extensive literature survey on the subject relating to the exploration, electric and non-electric utilization of geothermal resources in India and the world over and the constraints in the system approach for its exploration & exploitation. The various possibilities of its utilisation have been explored. Present technological statues of exploration & utilization scenario in India as well as in world has been synthesised and evaluated in the light of ongoing R & D work towards optimum utilisation of the resources in the world. This desk work was followed by:

  • Mail survey through structured and open ended questionnaires. Efforts were made to get back replies through reminders and even telephonic discussion, wherever required.

The questionnaires covered all possible segments in private and Govt. Sectors, Research Institutes and other related organisations in India. A number of agencies were also contacted.

  • Personal interviews and discussions were held with several persons active in the field of geothermal energy resources to gather further information and clarifications.
  • Discussions with the experts in various field were held and obtained literature on request.
  • Compilation, analyses and synthesis of data was carried out in accordance with the guideline of TIFAC.

The draft report would be finalised in accordance with the comments and suggestions, that would be received from TIFAC.

 

Limitations

During the survey a few difficulties were experienced in collecting information particularly on detailed aspects of technology and economics. Only a few organisations/individuals were willing to part with the detailed information. However, some insight could be obtained during personal meetings and persuasions. Thus, the report may be read in conjunction with the following limitations :

  • The study is based on published literature, mail survey, a limited number of personal visits and interviews.
  • No interview could be possible with foreign experts. The details of technical and economic parameters are limited to the extent of information that could be gathered during the survey.
  • The information of world scenario and evaluation thereof is based upon the published literature and the information collected through survey & literature requests.
  • The information on commercial aspects of the technologies were provided only by a few.

 

Market Survey Response

The response to market survey was not very encouraging. We got about 10% response from Indian organisations and about 70% response from foreign agencies (including embassies). It includes the response in reply to our reminders and also collection of information during personal meetings and interviews.

The information regarding technologies and commercial aspects was provided only by a few. Most of the respondents have sent published literature and literature the performance of utilization plants.

 

Findings of study/survey analysis

Earth is a reservoir of natural heat. Major geothermal fields are situated in circum-Pacific margin, rift zones of East Africa, Mediterranean basin Europe, mid-Atlantic rift, North Africa, across Asia to pacific. Geothermal resources are of four types; hydrothermal, geopressurised brines, hot dry rocks and magma. Geothermal reserves upto depth of 3 km have been estimated at 41.04 X 106 Quads, this figure for depth upto 10 km is 403 X 106 Quads. Where as the annual world energy consumption was 306 Quads in the year 1995. Thermal anomalies are generally associated with tectonic plates. Average thermal gradient below earth is 25-300C per km, but thermal gradient as high 200-8000C has been recorded. The world average of geothermal heat flow is 0.06 watt/m2 where as this figure is 30 Watt/m2 in Wairakei New Zealand. Geothermal electrical power plants are economically successful. Hydrothermal energy is being commercially used for electric & non-electric uses, in many parts of the world. Efforts are on to use geopressurised, hot dry rock & magma sources of geothermal energy.

Geothermal resources in India are under active study since 1970 and there are more than 340 known thermal spring localities in India. Temperature gradient in excess of 1000C/km and heat flow in excess of 200 mW/m2 has been recorded. Geofluid temperature upto 980C (boiling point at the altitude of occurrence) and bottom hole temperature of 1400C-2000C has been recorded. Ten geothermal provinces have been identified in India.

Exploration of geothermal resources requires skills of geology, geochemistry, geophysics, seismology, hydrology, reservoir engineering. In early stages of exploration low cost techniques are employed followed by expensive techniques for economic extraction of geothermal energy. Important sites being explored in India include Puga Chhumathang, Manikaran, Tapoban, Cambay, Tattapani, Bakreshwar, Tantloi, Tatta-Jaron, Athmallik, Unkeshwar. Physical and chemical properties of geothermal water, isotopic composition trace elements, and gases are analysed. Temperature-depth curves, isotherms, heat flow studies etc. are the basic tool deployed during exploration. Puga, Manikaran, Tattapani have been found suitable for electric generation.

Exploratory wells are drilled and these can be upto the depth of 500m-2000m, various data are recorded including pressure, temperature & flow of geofluid. Chemical & other physical properties are also recorded. Subsequently reservoir model is constructed. Bore hole drilling techniques are similar as followed in oil & gas drilling. A case study of geothermal drilling and drilling hazards is included in chapter IV. After geothermal drilling borefluid characteristics e.g. temperature, pressure, flow, enthalpy, quality, heat/power capacity, corrosiveness etc. are checked. A conceptual model of reservoir is constructed. Performance prediction, reservoir behaviour for a given rate of production, pressure transient analysis of geothermal well, permeability of reservoir are important parameters to be checked. Once optimum level of production of a reservoir is established geothermal fluid can be put to commercial use.

For collection controlling of geofluid well head gear is used. Arrangements for separation of water/steam, girt are made. Silencers, steam-mains, steam branch-lines, expansion bellows, loops, thermal legging, safety valves etc. are the important components of fluid collection. Transmission of two phase geofluid has also been used.

Electricity generation is the most attractive use of geothermal energy as transmission of electric energy to the users is simple as compared to transmission of heat energy. Also electric energy can be put to various applications. Geothermal electric generation was started in the beginning of this century in Italy at Larderallo. The world’s generating capacity of geothermal electricity at the end of 1997 was around 8000 MW. Italy, New Zealand, USA, Japan, Mexico, Philippines, Indonesia, Russia, El Salvador are the leading countries in the geothermal electric utilization apart from many other countries. Technology for electric generation from geofluid has been perfected these include condensing, non-condensing single/multi flashing, binary, single/double fluid cycles. Total flow system, hybrid combustion-geothermal system have also been tried. Reinjection of geofluid has been adopted due to environmental consideration and to prolong the life of reservoir. Various systems & subsystems of geothermal electric power plant are covered in chapter VI and Appendix I to IV.

Non-electric utilization of geothermal energy include space heating air conditioning agricultural usages; green house farming, horticulture, aquaculture, animal husbandry, industrial applications, chemical industry, extraction of mineral, food processing, pulp & paper manufacturing, balneology, tourism, bottled mineral water etc. The leading countries in non-electric use are China, Iceland, Japan, France, Hungary, CIS (formerly USSR), USA, New Zealand. Geothermal heat pump are popular in USA for space heating/cooling. In India direct application of geofluid include tourism (hot bath-balneology), mineral water and beginning has been made in space heating, green house farming, cold storage, poultry farming, mushroom cultivation, sulphur and borax extraction. Direct use of geothermal energy was to the tune of 12,000 MWth in the year 1991.

For efficient utilization of geothermal energy dual and multipurpose projects can play an important role. There are wide spectrum of possibilities. The main problem of utilization of geothermal energy in cascaded manner is mainly of demand balancing for various uses.

Control system safety equipment and safety precautions required to be adopted in geothermal installations for efficient & safe (both for human & machinery) operation are covered in chapter IX. Environment issues; impact on land air, water, and thermal discharges, noise, odour have been covered in chapter X including Methods of H2S abatement and impact on ecology are also covered. As compared to conventional sources of energy the environmental pollution & effect on ecology is very small in the case of geothermal utilization plants. Chapter No. XI covers the chemical & metallurgical problems faced in geothermal utilization plants and solution thereof.

Cost is always important but due consideration is also required to given to national self-sufficiency environmental impact, energy conservation & future source of non-fuel energy. Cost of geothermal energy includes exploration cost; land acquisition & drilling costs, fluid gathering & transmission cost, cost of plant and conversion equipment, man power, efficiency of the plant etc. Exploration costs are unpredictable and there are late returns on investments, as such exploration costs are to be supported by government and or international agencies UNDP/UNITAR. R&D is being done in USA, Japan, UK, Germany & Russia for utilization of hot dry rock type geothermal resources, geopressurised and magma resources. R&D is also directed towards improvement of drilling techniques for deep drilling upto 10 kms economically with reasonable speed.

 

Recommendations, Action Plan & Impact

Relevance of geothermal resources utilization to India is covered in chapter XV wherein it has been brought out that in view of gigantic exploration effort put in by GSI, and successful pilot projects for geothermal resources utilization, India should speed up utilization of geothermal resources. The recommendations for proper and effective utilization of geothermal resources include :

  • Formation of independent centralized body by MNES to co-ordinate all aspects of exploration, evaluation and exploitation of geothermal resources. It will be worth while to award few projects on turnkey basis to multinational companies.
  • Immediate steps should be taken to create proper infrastructure, which should include inter alia provision of deep drilling rigs to pursue the programme of establishing the potential geothermal resources.
  • In the areas where exploration has ben carried out by GSI and pilot utilization projects have been successfully completed. Actions are required to be initiated. MNES should encourage state agencies, entrepreneur for utilization of the resources for direct/electric application or mineral/elements or gas extraction.
  • A programme of advance training of Indian Earth Scientists and Engineers in specific area of interpretation of geoscientific data, reservoir modelling, drilling, monitoring of reservoirs, electric & non-electric utilization of geothermal energy to be chalked by MNES by establishing national or regional scientific technological research centres. Facilities of already established centres in New Zealand, Italy, Japan, Iceland, UK, USA and United Nations University in Japan/Iceland can also be availed.
  • Experimental use of geothermal heat pumps be introduced in selected areas.
  • Government should allow tax (excise, custom, sales, electricity etc.) holidays for geothermal exploration & exploitation projects. Allotment of land on concessional rates and subsidy on appliances used for exploration & utilization of geothermal energy be allowed.
  • Appropriate modifications be made in the administrative and legislative rules, and regulations governing mining/ground water resources and their utilization, so that it should not hinder the process of exploration and utilization of geothermal resources.
  • The already developed techniques of exploration and utilization of geothermal energy viz green house farming, poultry farming, mushroom cultivation, balneology, cold storage, power generation from low enthalpy resources, by different R&D Institutes/Organisations should be commercialized even by providing financial subsidies and other incentives to the industrial entrepreneurs.
  • R&D work of deep exploration of geothermal resources and large scale utilization in fields agricultural, industrial and electrical be encouraged. R&D work in exploration & exploitation of HDR, geopressurised and magma resources is also required to be initiated.
  • Incentives should be given by the government to agencies engaged in exploration of geothermal energy.

Active role of following agencies is crucial for advancing the cause of utilization of geothermal resources (the non-fuel energy resource of future) MNES, GSI, TIFAC (Ministry of Science & Technology), ONGC, NGRI, MECL, Central Ground Water Board, CEA, BHEL. The impact & spin offs, if all the recommendations are implemented are covered in chapter XVI.